the "saldatrice" generates a positive pole and a negative "unreported".
What does that mean?
when you look at the enel's tralicci you will see three (large but always three) pipelines are the three "phases" of the alternating current.
One is missing from the "neutro", in the house we have only one phase plus the neutral that "turn".
in total should exist five "cavi", the three phases the neutral and the "land".
the land, the "ground", soon ends, just outside the building, in the "pozzetto" of land.
The "neutro" just a little further in there, to save a few billion miles of "filo" the "neutro" ends up in "cabina", and where does it end? Down.
practically the neutral and the earth are the same thing (you can also try it and you will see that the earth and the neutral of the sockets there is a "right" so we, our body, for any "phase" we are "the other half of the world", the neutral.
as soon as we come into contact with a phase the electrons return to "central" using the ground but passing through us instead of through the cabin.
If, instead, a "unreported" current is produced, that is, with a transformer gi generates a new phase with a new "neutro" and does not put it "on the ground", this phase does not "see" the central enel, seeks the "your" neutral to return to the transformer.
It's a widespread security system, and the "saldator" uses that system.
However, a minimal loss of system insulation can suddenly "refer" the neutral to the ground and put us in trouble. needs a life saver in good condition, always.
The eye that the "mass" of the welder, the one that attacks the piece, is his "half", so we avoid touching it at the same time as the "torcy".
the current "continue" (direct, button or not) not "folgora", the lightning that makes "alternate" dangerous is caused by the 50 hz to which the heart is forced to pulsate. But it's even more dangerous, because it's "silent."
the current continues "magnetizes" blood and iron atom of hemoglobin, so the damage is very serious and, at the moment, not perceptible. That's why you chose the alternation.
who works with the dc (direct current) must be alert even more and never underestimate strange "debolezze" and sudden malori.